Spatial statistical modeling of arsenic accumulation in microsites of diverse soils
Spatial statistical modeling of arsenic accumulation in microsites of diverse soils
复制标题
DOI：
10.1016/j.geoderma.2022.115697
复制
发表时间：
2022-04
期刊：
影响因子：
6.1
通讯作者：
Aakriti Sharma;J. Guinness;Amanda Muyskens;M. Polizzotto;M. Fuentes;D. Hesterberg
中科院分区：
文献类型：
--
作者：
Aakriti Sharma;J. Guinness;Amanda Muyskens;M. Polizzotto;M. Fuentes;D. Hesterberg
确定控制土壤基质中营养物质和有毒元素流动性的反应机制受到矿物、非结晶固体、有机物和生物群的复杂组合的困扰。我们的目标是在微米空间尺度上推断不同成土环境土壤样品基质中有助于砷结合的化学元素和固体。砷与从不同排水类型的土壤中分离出来的8个石英砂颗粒发生反应，并在薄薄的风化涂层中成像，以测定不同含量的铁和铝（水合）氧化物、有机碳（OC）和其他元素。采用x射线荧光微探针（µ-XRF）成像和微尺度x射线吸收近边结构（μ-XANES）光谱对0.1 mM As(V)溶液处理前后的晶粒进行分析。从100 × 100 μ m2的沙粒涂层区域收集的多元素微xrf信号中建立的偏相关分析和回归模型推断出Fe、Zn、Ti、Mn或Cu对As保留的增强作用。大多数样品的飞行时间二次离子质谱（TOF-SIMS）分析表明，铁和铝之间存在显著的偏相关（r ' > 0.11），表明铁和铝（氢）氧化物在微观尺度上部分共定位。通过颗粒涂层收集的As K-edge μ-XANES光谱的线性组合拟合（LCF）结果通常包括吸附在针铁矿上的As(V)的80%，吸附在薄水铝石上的As(V)的不同比例的标准，结合在Fe（III）处理过的泥炭上的As(V)或As(III)，以及二甲基硅酸。Fe K-edge μ-XANES光谱的互补拟合包括所有样品中Fe（III）处理过的泥炭标准物≥50%，以及针铁矿。我们的集体结果推断，铁和可能的铝（氢）氧化物在控制砷固定中占主导地位，锌、钛、铜或锰的贡献不同，无论是在单个沙粒的覆盖层上，还是在不同成土环境下发育的土壤颗粒之间。总的来说，这些结果突出了土壤在微观尺度上的极端异质性，并对土壤管理减轻砷的不利环境影响具有重要意义。
Determining reaction mechanisms that control the mobility of nutrients and toxic elements in soil matrices is confounded by complex assemblages of minerals, non-crystalline solids, organic matter, and biota. Our objective was to infer the chemical elements and solids that contribute to As binding in matrices of soil samples from different pedogenic environments at the micrometer spatial scale. Arsenic was reacted with and imaged in thin weathering coatings on eight quartz sand grains separated from soils of different drainage classes to vary contents of Fe and Al (hydr)oxides, organic carbon (OC), and other elements. The grains were analyzed using X-ray fluorescence microprobe (µ-XRF) imaging and microscale X-ray absorption near edge structure (μ-XANES) spectroscopy before and after treatment with 0.1 mM As(V) solution. Partial correlation analyses and regression models developed from multi-element µ-XRF signals collected across 100 × 100 µm2areas of sand-grain coatings inferred augmenting effects of Fe, Zn, Ti, Mn, or Cu on As retention. Significant partial correlations (r′ > 0.11) between Fe and Al from time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis of most samples suggested that Fe and Al (hydr)oxides were partially co-localized at the microscale. Linear combination fitting (LCF) results for As K-edge μ-XANES spectra collected across grain coatings typically included >80% of As(V) adsorbed on goethite, along with varying proportions of standards of As(V) adsorbed on boehmite, As(V) or As(III) bound to Fe(III)-treated peat, and dimethylarsinic acid. Complementary fits for Fe K-edge μ-XANES spectra included ≥50% of the Fe(III)-treated peat standard for all samples, along with goethite. Our collective results inferred a dominance of Fe and possibly Al (hydr)oxides in controlling As immobilization, with variable contributions from Zn, Ti, Cu, or Mn, both across the coating of a single sand grain and between grains from soils developed under different pedogenic environments. Overall, these results highlight the extreme heterogeneity of soils on the microscale and have implications on soil management for mitigating the adverse environmental impacts of As.